[moderation] [net?] KASAN: slab-use-after-free Read in slip_open (2)

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Apr 29, 2024, 3:50:29 AMApr 29
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Hello,

syzbot found the following issue on:

HEAD commit: e88c4cfcb7b8 Merge tag 'for-6.9-rc5-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=178b0aef180000
kernel config: https://syzkaller.appspot.com/x/.config?x=19891bd776e81b8b
dashboard link: https://syzkaller.appspot.com/bug?extid=d72b9ee22d047a72b38d
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
CC: [da...@davemloft.net edum...@google.com ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-e88c4cfc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3d83e80db525/vmlinux-e88c4cfc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/847604848213/bzImage-e88c4cfc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d72b9e...@syzkaller.appspotmail.com

BUG: KASAN: slab-use-after-free in sl_sync drivers/net/slip/slip.c:730 [inline]
BUG: KASAN: slab-use-after-free in slip_open+0xea1/0x1140 drivers/net/slip/slip.c:806
Read of size 1 at addr ffff888060f14d91 by task syz-executor.2/6548

CPU: 0 PID: 6548 Comm: syz-executor.2 Not tainted 6.9.0-rc5-syzkaller-00042-ge88c4cfcb7b8 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xc3/0x620 mm/kasan/report.c:488
kasan_report+0xd9/0x110 mm/kasan/report.c:601
sl_sync drivers/net/slip/slip.c:730 [inline]
slip_open+0xea1/0x1140 drivers/net/slip/slip.c:806
tty_ldisc_open+0x9c/0x120 drivers/tty/tty_ldisc.c:432
tty_set_ldisc+0x2e6/0x680 drivers/tty/tty_ldisc.c:557
tiocsetd drivers/tty/tty_io.c:2439 [inline]
tty_ioctl+0xc2e/0x15f0 drivers/tty/tty_io.c:2739
tty_compat_ioctl+0x25c/0x4f0 drivers/tty/tty_io.c:2953
__do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1004
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf725b579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5e4d5ac EFLAGS: 00000292 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000005423
RDX: 0000000020000040 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>

Allocated by task 6539:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slub.c:3966 [inline]
__kmalloc_node+0x226/0x480 mm/slub.c:3973
kmalloc_node include/linux/slab.h:648 [inline]
kvmalloc_node+0x9d/0x1a0 mm/util.c:634
kvmalloc include/linux/slab.h:766 [inline]
kvzalloc include/linux/slab.h:774 [inline]
alloc_netdev_mqs+0xb3/0x1260 net/core/dev.c:10849
sl_alloc drivers/net/slip/slip.c:756 [inline]
slip_open+0x35d/0x1140 drivers/net/slip/slip.c:817
tty_ldisc_open+0x9c/0x120 drivers/tty/tty_ldisc.c:432
tty_set_ldisc+0x2e6/0x680 drivers/tty/tty_ldisc.c:557
tiocsetd drivers/tty/tty_io.c:2439 [inline]
tty_ioctl+0xc2e/0x15f0 drivers/tty/tty_io.c:2739
tty_compat_ioctl+0x25c/0x4f0 drivers/tty/tty_io.c:2953
__do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1004
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Freed by task 6538:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
poison_slab_object mm/kasan/common.c:240 [inline]
__kasan_slab_free+0x11d/0x1a0 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2106 [inline]
slab_free mm/slub.c:4280 [inline]
kfree+0x129/0x390 mm/slub.c:4390
kvfree+0x47/0x50 mm/util.c:680
device_release+0xa1/0x240 drivers/base/core.c:2580
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1fa/0x5b0 lib/kobject.c:737
netdev_run_todo+0x7d1/0x1260 net/core/dev.c:10600
slip_close+0x165/0x1c0 drivers/net/slip/slip.c:906
tty_ldisc_close+0x111/0x1a0 drivers/tty/tty_ldisc.c:455
tty_ldisc_kill+0x8e/0x150 drivers/tty/tty_ldisc.c:607
tty_ldisc_release+0x116/0x2a0 drivers/tty/tty_ldisc.c:775
tty_release_struct+0x23/0xe0 drivers/tty/tty_io.c:1696
tty_release+0xe33/0x1420 drivers/tty/tty_io.c:1867
__fput+0x270/0xb80 fs/file_table.c:422
__fput_sync+0x47/0x50 fs/file_table.c:507
__do_sys_close fs/open.c:1556 [inline]
__se_sys_close fs/open.c:1541 [inline]
__ia32_sys_close+0x86/0x100 fs/open.c:1541
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

The buggy address belongs to the object at ffff888060f14000
which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 3473 bytes inside of
freed 4096-byte region [ffff888060f14000, ffff888060f15000)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x60f10
head: order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888062fc1b81
ksm flags: 0x4fff80000000840(slab|head|node=1|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 04fff80000000840 ffff888014c50280 ffffea0001781000 0000000000000003
raw: 0000000000000000 0000000080040004 00000001ffffffff ffff888062fc1b81
head: 04fff80000000840 ffff888014c50280 ffffea0001781000 0000000000000003
head: 0000000000000000 0000000080040004 00000001ffffffff ffff888062fc1b81
head: 04fff80000000003 ffffea000183c401 dead000000000122 00000000ffffffff
head: 0000000800000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4691, tgid 1247449937 (udevd), ts 4691, free_ts 61356039317
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x2d4/0x350 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3317
__alloc_pages+0x22b/0x2460 mm/page_alloc.c:4575
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
alloc_slab_page mm/slub.c:2175 [inline]
allocate_slab mm/slub.c:2338 [inline]
new_slab+0xcc/0x3a0 mm/slub.c:2391
___slab_alloc+0x670/0x16d0 mm/slub.c:3525
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3610
__slab_alloc_node mm/slub.c:3663 [inline]
slab_alloc_node mm/slub.c:3835 [inline]
__do_kmalloc_node mm/slub.c:3965 [inline]
__kmalloc_node+0x36e/0x480 mm/slub.c:3973
kmalloc_node include/linux/slab.h:648 [inline]
kvmalloc_node+0x9d/0x1a0 mm/util.c:634
kvmalloc include/linux/slab.h:766 [inline]
seq_buf_alloc fs/seq_file.c:38 [inline]
seq_read_iter+0x830/0x12c0 fs/seq_file.c:210
kernfs_fop_read_iter+0x41a/0x590 fs/kernfs/file.c:279
call_read_iter include/linux/fs.h:2104 [inline]
new_sync_read fs/read_write.c:395 [inline]
vfs_read+0x6c0/0xb80 fs/read_write.c:476
ksys_read+0x12f/0x260 fs/read_write.c:619
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 4691 tgid 4691 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1141 [inline]
free_unref_page_prepare+0x527/0xb10 mm/page_alloc.c:2347
free_unref_page+0x33/0x3c0 mm/page_alloc.c:2487
__put_partials+0x14c/0x170 mm/slub.c:2906
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x4e/0x140 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x192/0x1e0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:322
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3798 [inline]
slab_alloc_node mm/slub.c:3845 [inline]
__do_kmalloc_node mm/slub.c:3965 [inline]
__kmalloc+0x1bd/0x440 mm/slub.c:3979
kmalloc include/linux/slab.h:632 [inline]
kzalloc include/linux/slab.h:749 [inline]
tomoyo_encode2+0x100/0x3e0 security/tomoyo/realpath.c:45
tomoyo_encode security/tomoyo/realpath.c:80 [inline]
tomoyo_realpath_from_path+0x1a7/0x710 security/tomoyo/realpath.c:283
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x2a7/0x3b0 security/tomoyo/file.c:771
tomoyo_file_open+0x71/0x90 security/tomoyo/tomoyo.c:334
security_file_open+0x78/0x630 security/security.c:2961
do_dentry_open+0x583/0x18c0 fs/open.c:942
do_open fs/namei.c:3642 [inline]
path_openat+0x1dfb/0x2990 fs/namei.c:3799
do_filp_open+0x1dc/0x430 fs/namei.c:3826
do_sys_openat2+0x17a/0x1e0 fs/open.c:1406

Memory state around the buggy address:
ffff888060f14c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888060f14d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888060f14d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888060f14e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888060f14e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 10 06 adc %al,(%rsi)
2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
6: 10 07 adc %al,(%rdi)
8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
c: 10 08 adc %cl,(%rax)
e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
1e: 00 51 52 add %dl,0x52(%rcx)
21: 55 push %rbp
22: 89 e5 mov %esp,%ebp
24: 0f 34 sysenter
26: cd 80 int $0x80
* 28: 5d pop %rbp <-- trapping instruction
29: 5a pop %rdx
2a: 59 pop %rcx
2b: c3 ret
2c: 90 nop
2d: 90 nop
2e: 90 nop
2f: 90 nop
30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi


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